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Zhang M.,Texas A&M University | Lu W.,Texas A&M University | Li J.-R.,Texas A&M University | Li J.-R.,Beijing University of TechnologyBeijing | And 5 more authors.
Inorganic Chemistry Frontiers | Year: 2014

Two nucleobase-incorporated metal-organic materials were designed, synthesized and structurally characterized. PCN-530 is among the few examples of metal-organic frameworks that utilize adenine as a constructional unit, while TMOP-1 is the first existing example of a crystallographically characterized nucleobase-incorporated metal-organic polyhedron. This work also offers a general perspective for the design and synthesis of nucleobase-incorporated metal-organic materials. This journal is © The Royal Society of Chemistry. Source

Wei Z.,Wuhan University | Wei Z.,Beijing University of TechnologyBeijing | Wei Z.,University of Oxford | Sprott J.C.,University of Wisconsin - Madison | Chen H.,Wuhan University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2015

Abstract This paper describes a class of third-order explicit autonomous differential equations, called jerk equations, with quadratic nonlinearities that can generate a catalog of nine elementary dissipative chaotic flows with the unusual feature of having a single non-hyperbolic equilibrium. They represent an interesting sub-class of dynamical systems that can exhibit many major features of regular and chaotic motion. The proposed systems are investigated through numerical simulations and theoretical analysis. For these jerk dynamical systems, a certain amount of nonlinearity is sufficient to produce chaos through a sequence of period-doubling bifurcations. © 2015 Elsevier B.V. Source

Ma Y.,Xiamen University | Xie Q.,Xiamen University | Liu X.,Xiamen University | Zhao Y.,Xiamen University | And 4 more authors.
Electrochimica Acta | Year: 2015

Amorphous ZnSnO3 double-shell and yolk-shell hollow microcubes were synthesized by calcination of their corresponding ZnSn(OH)6 precursors pre-prepared through a facile chemical solution method in argon. The as-prepared amorphous ZnSnO3 double-shell hollow microcubes have an average edge length of 1.6 μm. When used as the anode materials, amorphous ZnSnO3 double-shell hollow microcubes (D-ZnSnO3) reveal better electrochemical properties than ZnSnO3 yolk-shell counterparts (Y-ZnSnO3). D-ZnSnO3 anodes can retain a high reversible capacity of 741 mA h g-1 after 50 cycles with a coulombic efficiency of 99% at 100 mA g-1. The amorphous feature and unique box-in-box hollow architecture of D-ZnSnO3 play a key role in their excellent electrochemical properties. © 2015 Published by Elsevier Ltd. Source

Lei H.,Renmin University of China | Fang H.,Peking University | Han Y.,Renmin University of China | Lai W.,Renmin University of China | And 3 more authors.
ACS Catalysis | Year: 2015

Several copper corrole complexes were synthesized, and their catalytic activities for hydrogen (H2) evolution were examined. Our results showed that substituents at the meso positions of corrole macrocycles played significant roles in regulating the redox and thus the catalytic properties of copper corrole complexes: strong electron-withdrawing substituents can improve the catalysis for hydrogen evolution, while electron-donating substituents are not favored in this system. The copper complex of 5,15-pentafluorophenyl-10-(4-nitrophenyl)corrole (1) was shown to have the best electrocatalytic performance among copper corroles examined. Complex 1 can electrocatalyze H2 evolution using trifluoroacetic acid (TFA) as the proton source in acetonitrile. In cyclic voltammetry, the value of icat/ip = 303 (icat is the catalytic current, ip is the one-electron peak current of 1 in the absence of acid) at a scan rate of 100 mV s-1 and 20 °C is remarkable. Electrochemical and spectroscopic measurements revealed that 1 has the desired stability in concentrated TFA acid solution and is unchanged by functioning as an electrocatalyst. Stopped-flow, spectroelectrochemistry, and theoretical studies provided valuable insights into the mechanism of hydrogen evolution mediated by 1. Doubly reduced 1 is the catalytic active species that reacts with a proton to give the hydride intermediate for subsequent generation of H2. © 2015 American Chemical Society. Source

Ma H.,Beijing Research Institute of Uranium Geology | Yin L.,Ecole Polytechnique Federale de Lausanne | Gong Q.,Beijing University of TechnologyBeijing | Wang J.,Beijing Research Institute of Uranium Geology
International Journal of Mining Science and Technology | Year: 2015

Abstract Mixed-face ground encountered in Tunnel Boring Machine (TBM) tunneling presents great challenges and may trigger potential hazards without warning. A detailed understanding of such unfavorable conditions is therefore critical to a successful bored tunnel. In this paper, we firstly present a brief review of the definition, classification and the factors related to mixed-face conditions. Secondly, for a better understanding of this topic, we investigate the main difficulties and problems involved in TBM tunnelling under mixed-face ground with detailed cases. Thirdly, from the viewpoint of rock-machine interaction, we give some suggestions on the corresponding mitigation measurements from three categories: (i) selection of TBM type and modification of TBM, (ii) condition of ground and (iii) optimization of TBM operation. © 2015 Published by Elsevier B.V. on behalf of China University of Mining & Technology. Source

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